Methin dyes containing pyrroline nuclei



Ufl t ts m Paenw 'METHIN DYES CONTAINING PYRROLINE NUCLEI 7 Douglas James Fry, Bernard Alan Lea, and John David Kendall, all of Ilford, England, assignors to llford Limited, Ilford, England, a British company No Drawing. Filed May 18, 1959, Ser, No. 813,665

r Claims. c1.zs- -z40.4

This invention relates to new pyrrolenine dyes, to their manufacture and to photographic silver halideemulsions containing said dyes. V

Pyrrolenine bases of the general Formula I:

wherein R and R are the same ordifierentand are each a hydrogen atom or an alkyl group, R is a hydrogen atom or an alkyl or aryl group, and R and R are separate alkyl groups, may be made by treating a hydroxy pyrroline of the general Formula II:

where vthe groups R R R R and R have the meanings assigned ,to them above, with concentrated sulphuric acid or, where R is an aryl group, with a-strong aqueous non-oxidising mineral acid such as hydrochloric acid.

Typical compounds of these serise are: ,r

2 3 5 5-tetramethyl-pyrrolenine, B.P, 74 0.18.5 cm.

- Hg, n l.455O.

2 5 5-trimethyl-4-pheny1-pyrro1enine, B,P.-110 C./0.1

mm. Hg.

According to the persent invention there is provideda new series of methine dyes which contain apyrrolenine nucleus of Formula I connected to the remaindertof the dye molecule at the methylene group indicated in said formula in the 2-position.

Typical dyes thus provided conform to the following general formulae:

Formula III where R R R R and R have the meaningsgiven above, R is analkyl or aralkyl group,R is an'alkyl, aralkyl or aryl group, x is 1, 2, 3 or 4, L is a nitrogen atom or a methin group, and n is 1 or 2, D is the residue ofa 5- or 6-membered heterocycliciring which may be a pyrrolenine ring, and Y is an anion.

R1 iv nucleus. 7

(f) A compound of the general Formula X:

D, Ria V N-co-o= cn-cn)m=cn-N is". I Q Ru 3 2,979,501 tsetsd A r: 1 61 where R R R R R R7 and Y have the meanings given above and R, is hydrogen or an alkyl group.

where R R R R ,.R R7, R and m have the mean- "ings given above, and P and Q are each either an acyl,

alkoxycarbonylor cyano group.

According to a further feature of the present invention, theaforesaid methine 'dyes are prepared from intermediates of general Formula I by methods known perse "(as being in use or as described in the literature) for the conversion ofa heterocyclicbase containing an extra nuclear reactive methylene group to a methin dye.

More particularly the foregoing and other dyes according to this invention may be produced by condensing an alkyl or aralkyl quaternary salt of a compound of general Formula I with any of the following:

. e (a) A compound of general Formula VII:

tothem above, and R is an alkyl, aryl oraralkyl group.

(b) A compound of general Formula VIII:

77 R14 VIII where R D, L, n and Y have the meanings assigned to them above, R is a hydrogenatom or an acyl group,

R is a substituted or unsubstituted phenyl group, and

m is 2, 3 or 4.

., (0) 'An ester of an ortho acid or trithio ortho acid such as ethyl orthoformate or ethyl trithio orthoformate. (d) fi-Anilino acrolein anil or glutaconic aldehyde dianil.

(e) A compound of the general Formula IX:

where R is a hydrogen or an alkyl group, R is, an alkoxy,alkylthio, anilinoor acetanilido group, R is an alkyl,'. aryl or aralkyl group, a hydroxycarbonylalkyl group, or an alkoxycarbonylalkyl group, and D is the residue of a five-membered or six-'membered heterocyclic where R R have the meanings assigned tothem above, R and R are each :an acyl, alkoxycarbonyl orcyano group, and m is 1 or 2.

The dyes obtained by-using intermediates (a) and (b) are unsymmetrical monoor polymethincyanine dyes, using intermediates (c) are symmetrical trimethin cyanine dyes, using intermediates (d) are symmetrical pentaor heptamethincyanine dyes, and using intermediates (e), (f), (g) and (h) are merocyanine dyes.

In preparing the dyes the reactions are preferably I amass:

' at 5500 A. V

effected in a solvent medium and in the presence of a H "basic condensing agent, e.g. triethylamine.

In a modification of the invention the quaternary salts of the hydroxyp-yrrolines of general Formula I may be reacted in acetic anhydride with an alkylester of trithioformie acid or with diphenylformamidine, ,B-anilinoacrolein anil or with glutaconic aldehyde dianil to give intermediates of Formula XIII:

where Y is an acid radicle, M is an alkylthio or acetanilido group, x is 1, 2 or 3 (except that when M is alkylthio x is 1), R is an alkyl or aralkyl group, and the other symbols have the meanings assigned to them above.

These intermediates may be reacted with the quaternary salts of heterocyclic compounds having an active methyl or methylene group to form cyanine dyes or with a compound having an open-chain or cyclic reactive methylene group to form merocyanine dyes.

The dyes are valuable sensitisers for photographic silver halide emulsions, particularly gelatinos ilver chlorobnomide emulsions, and may be 'used in the manner known per se for methin dyes used as optical sensitisers for photographic emulsions. This invention includes photographic silver halide emulsions containing the-said dyes in sensitising amount.

The following examples will serve to illustrate the invention EXAMPLE 1 3-ethyl-5 (I :3:5:5-tetramethyl-Z-pyrrolinylidene) ethylidene] 2-tlziothiazolid-4-one and filtered. The crude-product (1.5 'g.) 'was crystallised .from a mixture of benzene ml.) and "cyclohexane 4 (50 ml.) to give crimson rods (0.9 g.) with M.P. 139- 141 C.

When incorporated in a silver chlorobromide emulsion the sensitivity was extended to 5 850 A. with a maximum at 5500 A.

EXAMPLE 2 3:,phenyl-5I (I :3:5:5-'tetramethyl-Lpyrrolinylidene) ethylidene] -2-thiotlziaz0lid-4-one The dye was .prepared as in Example 1 but .using 5- ethoxym'ethylene-3-phenyl-2-thio-thiazolid-4 one (2.4 g.)

in place of the corresponding 3-ethyl compound. The crude product (.1 g.) was twice crystallised from ethanol to give purple plates (0.45 g.) with M.P. 223-225 C.

When incorporated in a silverchlorobromide emulsion the sensitivity was extended to 5850 A. with a maximum EXAMPLE 3 2 3 -methyl benzth iazole -2 1 :3 :5':5 -'tetramethy lpyrrolenine) monomethincyanine iodide 2 3 5 S-tetramethyl-pyrrolenine methiodide (1.75 g.), methylthiobenzthiazole metho-toluene-p-sulphonate (3.7 g.), ethanol-(8 mls.) and triethylamine (1.4 ml.) were mixed, heated under reflux for 5-10 minutes, cooled and poured into dry ether. The precipitated oil crystallised when stirred with a small volume of ethanol and after recrystallising from ethanol the dye formed small yellow crystals with 'M.P. 304-307 C. (d);

When incorporated in a silver chlorobromide emulsion the sensitivity was extended to 4700 A. with a maximum ,at 4500 A.

EXAMPLE 4 1:3-dimethyl-5 I :3:5 :5-tetramethyl-pyrrolinylidene) ethylidene] -2-thi0hydant0in 2 3 5 5-tetramethyl-pyrrolenine methiodide (1.3

, g.), diphenyl formamidine (1.1 g.) and acetic anhydride (10 ml.) were mixed, heated under reflux for '15 minutes, cooled and poured into dry ether to precipitate a gum which was dissolved in ethanol (10 ml.). To 'thi's'solution was added '1 3-dimethyl-2-thiohydantoin (0.72 g.) and triethylamine (0.7 ml.), followed by heating under reflux for 10 minutes. The crude product crystallised on cooling the reaction'mixture in ice to give 0.76 g. dye with M.P. 210-218 .C. After crystallisation from benzene the product was obtained as minute red crystals (0.4 'g.) with M.P. 218-222 C.

When incorporated in a silver 'chloro'bromide emulsion the sensitivity was extended to 5650 A. with a maximum at 5300 A.

EXAMPLE 5 Bis-2 1 :3:5 :5 Jetramethyl-pyrrolenine) -trim-ethincyanine iodide 2 3 5 2 5-tetramethyl-pyrrolenine methiodide (2.65

g.), ethyl orthoformate-(3 ml.) and pyridine (10 ml.)

were mixed and heated gently under reflux for /z hour.

After cooling the solution was poured into 25 ml. of

saturated aqueous sodium iodide solution. After. filtration 'the crude product (0.47 g.) had M.P. 2l2-222 C. and

at 5500A.

product formed microscopic prisms (0.58 g.) with M.P.

When incorporated in a silver chlorobromide emulsion the sensitivity was extended to 5850 A. with a maximum s I EXAMPLE 7 2(3:3-dicyanoallylidene) :3:5 :5 -tetramethyl-pyrrline '2 3 S-tetramethyl-pyrrolenine methiodide (2.65 g.), diphenyl formamidine (2.2 g.) and acetic anhydride '(10' ml.) were mixed and heated under reflux for 15 minutes, cooled and poured into dry ether to precipitate a gum which was dissolved in ethanol m1.). To this solution was'added malondinitrile (0.5 g.) and triethylamine 1.4 ml.), the whole then being heated under reflux for 10 minutes, cooled well and filtered. The residue of crude product (0.5 g. M.P. 225-228 C.) was crystallised from ethanol (100 ml.) to give the dye as small yellow needles (0.42 g.) with M.P. 225 -227 C.

, EXAMPLE 8 2(5:5-dicyano-penta 2:4-dinylidene)-1:3:5:5- tetramethyl-pyrr oline 'Malondinitrile (0.66 g. fl-anilino acrolein aim (2.24 g), methanol (10 ml.) and triethylamine (1.4 ml.) were mixed, heatedunder reflux for minutes and then solve nt evap oratediofi under reduced pressure. The residue was next boiled under-reflux for 15 minutes with acetic anhydride (10 ml.) and the excess then distilled'ofl from the steambath under" reduced pressure- 2 3 5 5- tetramethylpyrrolenine methiodide (1.23 g.), ethanol (10 ml.) and triethylarnine (1.4 ml.) were added, the whole heated under reflux for 10 minutes, cooled in iceand filte'r e d. -The crude pr0duct (0.67 g. M.P. 228-230 C.)

minute dark red crystals (0.33-g.) with M.P. 245 248 C. When incorporated in a silver chlorobromide emulsion the sensitivity was ext ended to 5500,A.'with a maximum at 5350A."- i EXAMPLE 9 2(3:3-dicyanoallylidene -4-phenyl-1 :5 :5 -lrimethylpyrroline 1 4-phenyl-2 5: S-trimethyl-pyrrolenine (1.4. g.) was mixed with methyl iodide (3.4 ml.) and heated under reflux for 10 minutes. .After evaporation of excess methyl iodide under reduced pressure, diphenyl formamidine (1.9 g.) and acetic anhydride (8 ml.) were added and the whole heated under reflux for minutes. The cooled solution was poured into dry ether to precipitat *a gum which was dissolved in ethanol (l0.ml.). To this solution was added malondinitrile (0.35 g.) and triethylamine (1.05 ml.) and the mixture heated under reflux for 10 minutes. After cooling the product (0.28 g.) M.P. 224-234 C. was filtered oil and crystallised from ethanol (50 ml.) to give pale orange needles (0.16 g.) with M.P. 238-240 C.

EXAMPLE 10 1:3-diethyl-5 1 :3:5 :5 -tetramethyl-2-pyrrolinylidene) ethylidene] -2-thi0barbi1uric acid 2:3 5 5-tetramethyl-pyrrolenine methiodide (2.65

" ethyl acetate, the crude/product (0.75 g. M.P. 208-210 g.), diphenyl formamidine (2.2 g.) and acetic anhydride (10 ml.) were mixed and heated under reflux for 15 minutes, cooled and poured into dry ether to precipitate a guru which was dissolved in ethanol (10 ml.). To this solution was added 1 3-diethyl-2-thiobarbituric acid (1.5 g.) and triethylamine (1.4 ml.). the whole then being heated under reflux for 10 minutes, cooled in ice and filtered. The crude dye (1.3 g. M.P. 254-256 C.) was g.) with M.P. 203 c.

at 4800 A.

. EXAMPLE 11 3 1 :3:5 :5 -tetramethyl-2-pyrrblinylidene) ethylidene] ace tyiacetofie a 2 3 5 :;5-tetramethyl-pyrro1enine methiodide (2.65 g.), 3-ethoxymethylene acetylacetone (2 g.),.ethanol (10 ml.) and triethylamine (1.4 ml.) were mixed and heated under reflux for 10 minutes. After cooling the reaction mixture was diluted with water ml.) and a crystalline solid slowly separated. After filtration and washing with acetone, the product (0.66 g. M.P. '124126 C.) was purified by dissolving in a hot mixture of ethanol (2.5 ml.) and ethyl acetate (2.5 ml;) followed by dilution with light petroleum (40 ml. B.P. 4060 C.). The product separated as fine orange coloured needles (0.34 g.) with M.P. l35136 C.

When incorporated in a silver chlorobromide emulsion the sensitivity was extended to 4800 A.

EXAMPLE 12 4 (1 -methyl-quinaz0line) -2 1 :3:5 :5 -tetramethylpyrrolenine) monomethincyanine' iodide water (50 ml.).. The dye was twice extracted with chloroform (40 ml. portions) and'thecxtract evaporated to leave anzoil which crystallised when stirredwith a mixture of methanol and ethylacetate; The crude product (0.4 g. M.P. 202-204 C.)'was filtered off and recrystallised from ethanol (6 ml.) to give orange crystals (0.18

When incorporated in a silver chlorobromide emulsion the sensitivity was extended to 4 650 A. with a maximum at 4500 A. r

EXAMPLE 13;

2 (3 -methylbenzthiazole -2 1 :3:5 :5 -tetramethylpyrrolenine) trimethincya nine iodide 2 :-3 :5 5-tetramethyl pyrrolenine methiodide (2.65

g. diphenyl formamidine (2.2 g.) and acetic anhydride (10 ml.) were mixed and heated under reflux for 15 minutes,'cooled and poured into dry ether to precipitate a gum which was dissolved in ethanol (IO'mL). To this solution was added 2 3-dimethyl-benzthiazolium toluenep-sulphonate (3.4 g.) and triethylamine (1.4 ml.), the whole then being heated underireflux for 10 minutes, cooled and. filtered. Afterjwashing with acetone and C.) was crystallised'frorn ethanol (100ml.) togive the dye as reddish purple crystals (0.44 g.) with M.P. 220 C. When incorporated in a silver iodobromide emulsion the sensitivity was extended to 5750 A. with a maximum I at 5400 A.

EXAMPLE 14 3-ethyl-2-thi0-5 (1-ethyl-3:5:5-trimethyl-2-pyrr0linylidene) ethylidene] thiaz0lid-4-0ne 7 caused the dye to separate as red coloured crystals with M.P. f140C.. Y

When incorporated in a silver chlorobromide emulsion the sensitivity was extended to 5950 A. with a maximum at 5500 A.

EXAMPLE 15 3-ethyl-2-thi0-5 1 -benzyl-3:5 :5 -trim ethyl-Z-pyrrolinylidene) ethylia'ene] thiazlid-4-0ne '2 3 -tetramethyl-pyrrolenine (1.23 g.) and benzyl bromide (2 ml.) were mixed and heated on a steam bath for 5 minutes. The quaternary salt formed was washed with dry ether =by decantation. To this was added 5- ethoxymethylene-3-ethyl-2-thio-thiazolid-4-one (2.17 g.) ethanol ml.) and triethylamine 1.4 ml.) and the solution heated under reflux for 10 minutes, cooled and diluted with water to precipitate an oil which slowly crystallised when stirred with acetone. The dye was purified as in Example 14 to give dark red crystals with M.P. 186 c.

EXAMPLE 16 I-phenyl-3-methyl-4-[(I:3:5:5-tetramethyI-Z-pyrrolinylidene)ethylidene] -pyraz0l-5-0ne 2 3 :5 5-tetramethyl-pyrrolenine methiodide (2.6 g.), diphenyl formamidine (2.2 g.) and acetic anhydride (10 ml.) were mixed and heated under reflux for 20 minutes, cooled and poured into dry ether to precipitate a guru which was dissolved in ethanol (10 ml.). To this solution was added l-phenyl-3-methyl-pyrazol-5-one (1.4 g.) and triethylamine (1.4 ml.) followed by heating under reflux for 10 minutes. After cooling, the solution was diluted with water to precipitate an oil which partly crystallised. This paste was filtered, and

washing with a small volume of cyclohexane left 0.3 g. of'crude'product'with M.P. 155 C. Crystallisation from cyclohexane (120 ml.) gave the dye as orange crystals (0.15 g.) with M.P 156 C.

EXAMPLE l7 3-carboxymethyl-2-thi0-5[(I :3:5:5-tetramethyl-Z-pyrrolinylidene)ethylidene] thiazolid-4-0ne 2 3 5 5-tetramethyl-pyrrolenine 'methiodide (2.6 g.), diphenyl formamidine (2.2 g.) and acetic anhydride (10 ml.) were mixed and heated under reflux for 20 minutes, cooled and poured into dry ether to precipitate agum which was dissolved in ethanol (10 ml.). To this solution was added 3-carboxymethyl-2-thiothiazo1id- 4-one (1.9 g.) and triethylamine (2.8 ml.) followed by heating under reflux for 10 minutes. After cooling the solution was poured into an ice-cold solution of concentrated hydrochloric acid (1.2 ml.) in water (100 ml.).

' The product separated as an oil which solidified on standing to give 1.9 g. of 'dye with M.P. 136-139 C.

8 What we claim is: V 1. A dyestufi of the formula:

wherein R R R are each selected from the class consisting of hydrogen and lower alkyl groups, R is selected from the class consisting of hydrogenylower alkyl and phenyl groups, R R .are each lower alkyl groups, R, is selected from the class consisting of lower alkyl and benzyl groups, R is selected from the class consisting of lower alkyl, phenyl, benzyl, hydroxy carbonyl lower alkyl and lower alkoxy carbonyl lower alkyl groups, m is an integer selected from the group consistingof 1, v2 and 3, .and D represents the non-metallic pyrrolinylidene) ethylidene]-pyrazol5-one.

References Cited in the file of this patent UNITED STATES PATENTS 2,298,731 Brooker et a1. Oct. 13,1940

2,409,612 .Brooker .et al. Aug. 15, 1941 2,739,147 Keyes Mar. 20, 1956 2,739,148 .Reed Mar. .20, 1956 FOREIGN PATENTS 524,483 Belgium Dec. 15 1 953 516,228 Italy Feb. 19, 1955 I OTHER REFERENCES Chemical Abstracts, vol. 8, pp. 1763 to 1764 (1914), Abstract of Plancher et al., Atti accad. Lincei, vol. 22,

Brooker et al.: Journal of the Am. Chem. .Soc., vol. 67, pages 1869-1879 (1945) (particularly note pp. 1869- Venkataraman: Synthetic Dyes, vol. II, .pages .1143 to 1185, Academic Press '.Inc., 1952.

Strell .et al.: Chemische Berichte, vol. 87, ,pp. 1025 .to 1032 (1954). V 1 

1. A DYESTUFF OF THE FORMULA: 